1. Field of the Invention
The present invention relates to a wellhead component for holding and supporting the weight of a downhole rod or tubular. More particularly, the present invention relates to a clamping device to hold and support the weight of a downhole rod to facilitate the removal or repair of a surface drive assembly.
2. Background of the Related Art
Oil and gas in newly discovered reservoirs usually flow to the surface by natural lift. The natural formation pressure of a reservoir provides the energy or driving force to move reservoir fluids horizontally into a wellbore, through production tubing, and through surface processing equipment. During the life of any producing well, however, the natural reservoir pressure decreases as reservoir fluids are removed from the formation. As the natural downhole pressure drops to the sum of the hydrostatic head in the wellbore and the facility pressure, the fluids cease to spontaneously flow to the surface. Therefore, artificial lift methods such as sucker-rod pumping, downhole pumping, and gas injection lift techniques, for example, are employed to lift the fluids to the surface.
Many wells today use a downhole pumping apparatus such as a progressing cavity pump (PCP) system to lift fluids from within the production well to the surface. A PCP system consists of a progressing cavity pump located within the wellbore and a motor-driven drive assembly located at the surface of the well. The pump and the motor are connected by a rod string disposed within the production tubing. The progressing cavity pump consists of a rotor disposed within a stator located within the production tubing. The rotor is driven by the rod string which is supported and rotated by the motor-driven drive assembly. The well is produced by rotating the rod string which drives the rotor of the pump resulting in a non-pulsating positive displacement flow of fluids toward the surface of the well.
A problem occurs when the drive assembly requires routine servicing or maintenance after a period of use. Typically, when servicing an assembly, the motor is first shut down and the rod string is allowed to backspin. The rod string is much like a rubber band or other elongated elastic member due to its length. As a result, the rod string possesses accumulated potential energy due to the continuous twisting motion created by the drive motor. The accumulated xe2x80x9cwinding upxe2x80x9d converts into kinetic energy once the drive motor is released or removed. Consequently, the rod string unwinds by rotating in an opposite direction.
Even after the rod string has stopped back-spinning upon the initial shutdown, a sudden jerk or bump to the drive or rod string itself may release residual energy retained in the system and cause the rod string to uncontrollably back-spin. This presents a safety risk to the personnel standing on the wellhead trying to disconnect the drive from the rod string. Also, the spinning rod may damage other equipment nearby.
One method to safely remove a drive assembly from a rod string is to independently hold and support the weight of the rod string prior to removing the drive. Presently, the rod string is clamped to a rig which is secured to a vehicle. Once the rod string has been supported by the vehicle, a second vehicle is typically used to lift and remove the drive assembly from the supported rod string. These steps are then repeated in reverse order to re-connect the drive to the rod string. This method is complex, costly, and time consuming.
Therefore, there is a need for a method and apparatus to facilitate the servicing and/or replacement of progressing count pump components. There is a further need for holding and supporting the weight of a rod string to facilitate an efficient and safe removal of a drive assembly from the rod string.
A rod hanger and clamp is provided to hold a rod or tubular within a well, allowing a well service provider or operator to safely and more cost effectively disassemble, remove, or otherwise work on a drive assembly. In one aspect, the rod hanger and clamp comprises an annular body having at least one radial aperture formed there-through and a rod holder disposed through each aperture. The rod holder comprises a push jaw disposed on a first end of a threaded member. A well service provider or operator may apply a torque to the threaded member to urge the push jaw against an outer surface of a tubular disposed within a well, thereby holding the tubular in place.
In another aspect the invention provides a method of holding and supporting a tubular within a wellbore comprising shutting down a drive assembly, allowing the tubular to back-spin, and supporting the tubular with an annular body having at least one radial aperture formed therethrough and, at least one threaded member disposed within the aperture. The threaded member has a push jaw to secure the tubular.